Oil spill is a global problem related to the vast amounts of oil that are produced off shore as well as the large amounts of oil being transported on ships independent of the site of production.
There have been made many attempts to solve the problem related to such pollution irrespective of their origin are loss during production, uncontrolled blow outs, leakages from ships during transportation or in case of shipwrecking by natural courses or as a consequence of actions of war or terror.
Many good attempts have been made but since the problem is huge and multifarious the final solution that ends the problem once and for all will probably never be found. The largest problems encountered recently are large and concentrated oil spills close to a coast line, in case of shipwrecking or the like, where several tons of oil is lost as a whole, often in bad weather conditions, causing very severe damage to the life in the sea as well as along the coastline. It is a major challenge to provide better ways to handle also these kinds of spills.
Measures that have been proposed includes methods of chemical as well as of physical/mechanical treatment of oil spill and commonly a combination of chemical and physical/mechanical treatment. With respect to the chemical methods of treatment these may broadly be split in two categories. One category involves dispersion of the oil so that it will sink and be degraded in the water as separate droplets (U.S. Pat. No. 5,618,468 and U.S. Pat. No. 6,194,473). Methods belonging to this category are best suited for spills far from the shore where there are significant depths of water available for the oil to be dispersed in. A chemical method for treatment of oil spill that is based on the opposite principle, may be designated stiffening of the oil, which means that chemicals are added to ensure that the oil does not become dispersed but remains as a whole and more or less solid and thereby may be more easily removed by mechanical means in a next step. With “mechanical means” herein is understood a treatment with oil weirs, pumps, drawworks, excavating and lifting mechanisms of any kind that may be used to transport the oil from a water surface into any kind of container for recovery or destruction. With “physical treatment” herein is understood addition of substances that has an effect on the oil without causing a chemical reaction, such as absorbents or the like in which the oil may be absorbed.
Polymers may be used to make oil stiffen or solidify. U.S. Pat. No. 5,453,129 teaches in situ fibre spinning of a polymer web on top of an oil spill and subsequent collection of the polymer/oil combination. A comprehensive overview of chemicals and mixtures used for stiffening of oil spills is published in “The effectiveness of solidifiers for combatting oil spills”, Ali Ghalambor, University of Southwestern Louisiana, USA, Technical Report Series 96-006. Common for most of these chemicals and mixtures is that they are applied as a solid substance with a requirement of at least 1 kg of chemical or mixture per 3 kg of oil.
The manner of operation for some of the chemicals and mixtures involve a chemical reaction. One example is use of solutions of adhesives that are dried in presence of common catalysts such as cobalt naphtenate (U.S. Pat. No. 3,755,189). Usually the catalyst is mixed into the adhesive solution but it may also be added directly to the oil spill before or after adding the adhesive solution. The advantage of this method is that the adhesive solution has a longer shelf life and therefore may be stored for a longer period of time after being manufactured. A typical composition from U.S. Pat. No. 3,755,189 comprises 65-85% of a suitable solvent, 2-6% cobalt naphtenate while the adhesive constitutes the remaining ad 100%. The added composition leads to the formation of a film on top of the oil spill and subsequent confinement of the oil. The disadvantage is the use of large quantities of solvents that firstly are highly flammable when being applied and that secondly dilute the oil and thereby delay the confinement.
A frequently used way of stiffening and removing or confining of oil spill is based on use of materials with a high surface area/weigh ratio which in addition may be surface modified by certain chemicals and/or reaction mixtures (U.S. Pat. No. 4,780,518; U.S. Pat. No. 5,961,823; DE 28 45 975).